1. Field of the Invention
This invention relates to a woven tubing for a stent type blood vascular prosthesis and to a stent type blood vascular prosthesis using the woven tubing.
2. Description of Related Art
As a means for the remedy of an aortic aneurysm or an aortic dissection, a method which comprises surgically cutting a lesion in the blood vessel and filling the remaining dent therein with a blood vascular prosthesis has been heretofore regarded as a standard. The surgical operation with ventrotomy or thoracotomy inflicts a large burden of invasion on the patient and entrains danger. In particular on the part of old people who suffer from chronic diseases, the application of this surgical operation has been restricted because of inducing a complication. In recent years, as the cure of aorticaneurysm or aortic dissection with low invasion, an intravascular therapy or surgery has been attracting attention. With the intravascular therapy, it is possible to prevent the inflow of blood to the lesion and protect the lesion against fracture by guiding a blood vascular prosthesis endowed with a stent, namely a stent type blood vascular prosthesis, into the lesion in the blood vessel via a catheter and covering the lesion with the stent blood vascular prosthesis thereby thrombogenesing the lesion.
The stent type blood vascular prosthesis, which is used for this intravascular therapy, is inserted as folded in a small size into the catheter, conveyed to the lesion, and then allowed to unfold and restore the original tubular shape. The term “stent” as used herein refers to a tubular supporting skeleton, which is inserted into an intracorporeal tubular organ such as the blood vessel for supporting the organ. In the blood vascular prosthesis, the stent functions to hold the blood vessel in its tubular shape mechanically and implant the blood vascular prosthesis fast against the wall of the blood vessel. However, the stent type blood vascular prosthesis has limited folding ability and insufficient adaptability to curved blood vessels in human bodies because it is inferior in flexibility to the blood vascular prosthesis that is devoid of stent.
U.S. Pat. No. 5,976,179 discloses an implanting device (equivalent to the “stent type blood vascular prosthesis” designated in the present specification) which has a plurality of intermittently disposed bendable wire rings (equivalent to the “stent” designated in the present specification) concatenated with the tubular surface member (equivalent to the “woven tubing” designated in the present specification). Unlike the conventional stent, which is provided with supporting skeletons concatenated continuously in the direction of length, in the stent disclosed in the publication individual wire rings for constructing such a stent are not concatenated. This stent relies on this construction to attain an implanting device which prevents degradation of flexibility and excels in folding ability and adaptability to curved blood vessels in human bodies. Further, by using a monofilament having a shape retaining property as warps and a dense multifilament as wefts in the surface member, the surface member is aimed at attaining such a shape retaining property as avoids being crushed by the flow of blood and such a liquid tightness (low water permeability) as avoids leakage of blood to the exterior in the implanting devices even when the wire rings are not concatenated.